<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      table {
        border: 1px solid #000;
        text-align: center;
        width: 300px;
      }
      th,
      td {
        border: 1px solid #000;
      }
      h3 {
        position: relative;
      }
      span {
        position: absolute;
        left: 145px;
        top: -4px;
        width: 16px;
        height: 16px;
        color: white;
        font-size: 12px;
        text-align: center;
        border-radius: 50%;
        background-color: #e63f32;
      }
    </style>
  </head>
  <body>
    <div id="app">
      <h3>小黑的礼物清单🛒<span>?</span></h3>
      <table>
        <tr>
          <th>名字</th>
          <th>数量</th>
        </tr>
        <tr v-for="(item, index) in list" :key="item.id">
          <td>{{ item.name }}</td>
          <td>{{ item.num }}个</td>
        </tr>
      </table>

      <p>礼物总数：{{ totalCount }} 个</p>
      <hr />
      <hr />
      <p>礼物总数：{{ total() }} 个</p>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <script>
      const app = new Vue({
        el: "#app",
        data: {
          // 现有的数据
          list: [
            { id: 1, name: "篮球", num: 3 },
            { id: 2, name: "玩具", num: 2 },
            { id: 3, name: "铅笔", num: 5 },
          ],
        },
        methods: {
          total() {
            console.log("methods方法多个地方调用就会触发多次");
            let res = this.list.reduce((sum, item) => sum + item.num, 0);
            return res;
          },
        },
        // 计算属性结构 - 性能优化 - 有缓存
        computed: {
          totalCount() {
            console.log("computed计算属性执行了");
            let res = this.list.reduce((sum, item) => sum + item.num, 0);
            return res;
          },
        },
      });
    </script>
  </body>
</html>
